Fix version check for znver3, which needs gcc >= 10.3 (#628)

Apple's clang-12 lacks znver3 support, unlike upstream clang-12.

build/config.mk.in

@@ -94,7 +94,7 @@ CC                := @CC@
 GCC_OT_4_9_0      := @gcc_older_than_4_9_0@
 GCC_OT_6_1_0      := @gcc_older_than_6_1_0@
 GCC_OT_9_1_0      := @gcc_older_than_9_1_0@
-GCC_OT_10_1_0     := @gcc_older_than_10_1_0@
+GCC_OT_10_3_0     := @gcc_older_than_10_3_0@
 CLANG_OT_9_0_0    := @clang_older_than_9_0_0@
 CLANG_OT_12_0_0   := @clang_older_than_12_0_0@
 AOCC_OT_2_0_0     := @aocc_older_than_2_0_0@

config/zen3/make_defs.mk

@@ -71,7 +71,7 @@ ifeq ($(CC_VENDOR),gcc)
   ifeq ($(GCC_OT_9_1_0),yes)  # gcc versions older than 9.1.
     CVECFLAGS_VER  := -march=znver1 -mno-avx256-split-unaligned-store
   else
-  ifeq ($(GCC_OT_10_1_0),yes) # gcc versions 9.1 or newer, but older than 10.1.
+  ifeq ($(GCC_OT_10_3_0),yes) # gcc versions 9.1 or newer, but older than 10.3.
     CVECFLAGS_VER  := -march=znver2
   else                        # gcc versions 10.1 or newer.
     CVECFLAGS_VER  := -march=znver3
@@ -84,10 +84,14 @@ ifeq ($(CC_VENDOR),clang)
   else
   ifeq ($(CLANG_OT_12_0_0),yes) # clang versions 9.0 or newer, but older than 12.0.
     CVECFLAGS_VER  := -march=znver2
+  else
+  ifeq ($(OS_NAME),Darwin)      # clang version 12.0 on OSX lacks znver3 support
+    CVECFLAGS_VER  := -march=znver2
   else                          # clang versions 12.0 or newer.
     CVECFLAGS_VER  := -march=znver3
   endif
   endif
+  endif
 else
 ifeq ($(CC_VENDOR),aocc)
   ifeq ($(AOCC_OT_2_0_0),yes)   # aocc versions older than 2.0.

configure

@@ -1791,8 +1791,8 @@ check_compiler_version_ranges()
 	#   [5] https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gcc/x86-Options.html#x86-Options
 	#   [6] https://gcc.gnu.org/onlinedocs/gcc-9.4.0/gcc/x86-Options.html#x86-Options
 	#
-	# range: gcc < 10.1 (ie: 9.4 or older)
-	# variable: gcc_older_than_10_1_0
+	# range: gcc < 10.3 (ie: 9.4 or older)
+	# variable: gcc_older_than_10_3_0
 	# comments:
 	#   These older versions of gcc do not explicitly support the Zen3
 	#   microarchitecture; the newest microarchitectural value understood by
@@ -1806,7 +1806,7 @@ check_compiler_version_ranges()
 	gcc_older_than_4_9_0='no'
 	gcc_older_than_6_1_0='no'
 	gcc_older_than_9_1_0='no'
-	gcc_older_than_10_1_0='no'
+	gcc_older_than_10_3_0='no'
 
 	clang_older_than_9_0_0='no'
 	clang_older_than_12_0_0='no'
@@ -1839,10 +1839,10 @@ check_compiler_version_ranges()
 			gcc_older_than_9_1_0='yes'
 		fi
 
-		# Check for gcc < 10.1.0 (ie: 9.4 or older).
-		if [ ${cc_major} -lt 10 ]; then
-			echo "${script_name}: note: found ${cc} version older than 10.1."
-			gcc_older_than_10_1_0='yes'
+		# Check for gcc < 10.3.0 (ie: 10.2 or older).
+		if [[ ( ${cc_major} -lt 10 ) || ( ${cc_major} -eq 10 && ${cc_minor} -lt 3 ) ]]; then
+			echo "${script_name}: note: found ${cc} version older than 10.3."
+			gcc_older_than_10_3_0='yes'
 		fi
 	fi
 
@@ -3835,7 +3835,7 @@ main()
 		| sed -e "s/@gcc_older_than_4_9_0@/${gcc_older_than_4_9_0}/g" \
 		| sed -e "s/@gcc_older_than_6_1_0@/${gcc_older_than_6_1_0}/g" \
 		| sed -e "s/@gcc_older_than_9_1_0@/${gcc_older_than_9_1_0}/g" \
-		| sed -e "s/@gcc_older_than_10_1_0@/${gcc_older_than_10_1_0}/g" \
+		| sed -e "s/@gcc_older_than_10_3_0@/${gcc_older_than_10_3_0}/g" \
 		| sed -e "s/@clang_older_than_9_0_0@/${clang_older_than_9_0_0}/g" \
 		| sed -e "s/@clang_older_than_12_0_0@/${clang_older_than_12_0_0}/g" \
 		| sed -e "s/@aocc_older_than_2_0_0@/${aocc_older_than_2_0_0}/g" \